In drilling wells for oil and gas exploration, understanding the structure and properties of the associated geological formation provides information to aid such exploration. Optimal placement of a well in a hydrocarbon-bearing zone (the “payzone”) and maintaining the well in the zone usually requires geosteering with deviated or horizontal well trajectories, since most payzones extend in the horizontal plane. Geosteering is an intentional control to adjust drilling direction. Measurements of formation properties can be used to geosteer a well to and maintain the well in the zone.
Various measurement techniques have been developed that can be applied to measurements of formation properties. For example, compensated measurements techniques have been developed for logging devices. In a typical compensated measurement of a logging device, a pair of receivers are located between two transmitters, where the transmitters are alternately energized in opposite directions, and the signals received at the receivers can be processed, such as by averaging, to reduce or eliminate perturbations in reading due to variations in borehole size or tilt of the tool that contains the receivers. See for example U.S. Pat. No. 4,899,112 related to well logging for determining formation resistivity at a shallow and a deep depth. However, boundaries can affect the measurement of the formation properties. Thus, advances in apparatus and methods that address such problems would enhance oil and gas exploration.